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Dr John LoughreyThe Rotunda Hospital
Dublin
Ultrasound guided blocks for the Obstetric Anaesthetist -Practical Tips and Tricks
History/Refinements
• First Spinal Anaesthetic 1899
• Bupivacaine/Catheter Techniques 1950’s
• Neuraxial Opioids 1980’s
Ultrasonography of the Adult Thoracic andLumbar Spine for Central Neuraxial Blockade.
Chin KJ, Karmaker MJ, Peng P.Anesthesiology June 2011;114:1459-85.
“ Evidence on Ultrasound-‐guided catheterisa5on of the epidural space is limited in amount, but suggests that it
is safe and may be helpful in achieving correct placement.”
Equipment Cost
Technique Tip - Equipment
Ultrasound in Neuraxial Anaesthesia
• Identifying Correct Lumbar Interspace
• Identifying Skin Puncture site
• Measuring depth to Epidural Space
• Identifying reasonable Anatomy
Ultrasonographic control of the puncture level for lumbar neuraxial block in obstetric
anaesthesia.SchloAerbeck H, Schaeffer R, Dow WA, et al
Br J Anaesth. 2008; 100: 230-‐4.
Damage to the conus medullaris following spinal anaesthesia.
Reynolds F . Anaesthesia 2001; 56: 238-‐247.
Technique
Technique
Technique
• Grade 1. Spinous processes visible or palpable with light touch
• Grade 11. Midline and interspinous indentation identified with deep palpation
• Grade 111. Interspinous indentation not palpable. Midline estimated from higher spinous levels
Who benefits ?Tip - Do Lots of Easy Cases
Ultrasound imaging facilitates spinal anaesthesiain adults with difficult surface anatomical landmarksChin KJ et al. Anesthesiology. 115(1)94-101. July 2011
37; group LM, n ! 50). These results are presented in table3. As shown, the direction and magnitude of between-groupdifferences were similar to those of the overall analysis, theonly exception being the lack of a statistically significantdifference in time taken to perform the spinal anesthetic.
A change in spinal needle was required in 4 (6.7%) pa-tients in group US and 16 (26.7%) in group LM (P !0.003). In group US, a longer needle (25-gauge, 120 mm)was requested for one patient and a larger-gauge needle (22-gauge, 90 mm) for one patient. In group LM, a longer needle(120 mm) was requested for 11 patients (25-gauge in 8 and22-gauge in 3) and a larger-gauge needle (22-gauge) in 5 (90mm in 2, and 120 mm in 3). A needle similar to the first one(25-gauge, 90 mm) was requested in all other patients.
Dural puncture could not be achieved with a spinal needlein two patients in group LM despite five needle insertionattempts. Both patients were obese (BMI 39 and 41 kg/m2)and had surface landmarks that were difficult or impossibleto palpate. A combined spinal-epidural technique was usedin both patients, and this eventually resulted in successfulspinal anesthesia. The combined spinal-epidural needle in-sertion and redirection attempts were not included in the
analysis. Dural puncture was unsuccessful in one patient ingroup US despite four needle insertion attempts (two each atL3–L4 and L4–L5 interspaces). The patient was moderatelyobese (BMI 36 kg/m2) with landmarks that were difficult topalpate. The ligamentum flavum–dura mater complex andposterior aspect of the vertebral body could not be visualizedat the L2–L3 and L3–L4 interspaces and were only faintlyvisible at the L4–L5 interspace. Subsequent attempts by asecond anesthesiologist using a combined spinal-epiduraltechnique (again not included in the analysis) also were un-successful, and the patient received a general anesthetic.
There were no significant differences between groups ineither block-associated pain scores (group US, 3 [1–4)] vs.group LM, 3 [1–5]) or patient satisfaction scores (4 [3–5] inboth groups). All patients in whom dural puncture was suc-cessfully achieved experienced complete sensory loss to theT7 dermatome or higher. None of the patients experiencedany adverse events as a direct result of the study protocol.
Discussion
The technical difficulty of neuraxial blockade is measuredusing two main parameters: the number of needle manipu-lations required for success and the time taken to perform theblock. Of the two, the former is more important becausemultiple needle insertions are an independent predictor ofcomplications, such as inadvertent dural puncture, vascularpuncture, and paresthesia.1 Elicitation of paresthesia, inturn, is a significant risk factor for persistent neurologic def-icit after spinal anesthesia.9,11
Approximately halfway through the study, it became ap-parent that the first-attempt success rate using the surfacelandmark-guided technique was going to be lower than an-ticipated. In retrospect, this is not surprising because webased our initial estimate on studies in the general adultpopulation1,2,15,16 instead of the subset of patients with pre-dictors of difficulty. Recently published data from Ellinas etal.3 indicate that the first-pass success rate for neuraxialblockade in parturients with a BMI of 35 kg/m2 or greater isapproximately 35%, which is consistent with our observa-
Table 2. Outcomes Reflecting Ease of Performance of Spinal Anesthesia
Ultrasound-guided Technique(n ! 60)
Landmark-guided Technique(n ! 60)
PValue
Successful dural puncture — — —On 1st needle insertion attempt 39 (65%) 19 (32%) " 0.001On 1st needle pass 16 (27%) 5 (8%) 0.008Within 5 needle passes 30 (50%) 16 (27%) 0.009Within 10 needle passes 45 (75%) 26 (43%) " 0.001Total number of needle insertion attempts 1 #1–2$ 2 #1–4$ " 0.001Total number of needle passes 6 #1–10$ 13 #5–21$ " 0.001Time taken to establish landmarks (min) 6.7 % 3.1 0.6 % 0.5 " 0.001Time taken to perform spinal anesthetic (min) 5.0 % 4.9 7.3 % 7.6 0.038Total procedure time (min) 12.2 % 6.0 7.9 % 7.7 " 0.001
Data are reported as n (%), mean % standard deviation, or median #interquartile range$.
Fig. 2. Comparison of the number of patients requiring one,two, three, or more than three needle insertion attempts forsuccessful dural puncture, depending on whether an ultra-sound-guided (group US) or a surface landmark-guided(group LM) technique of spinal anesthesia was used.
Ultrasound Facilitates Difficult Spinal Anesthesia
Anesthesiology 2011; 115:94 –101 Chin et al.98
Ultrasound Using the Transverse Approach to the Lumbar Spine Provides Reliable Landmarks for
Labor Epidurals. Anesthesia & Analgesia. May. 2007.
Cris5an Arzola, Sharon Davies, Ayman Rofaeel, Jose Carvalho.
Sonoanatomy of the Lumbar Spine in patients with previous unintentional dural punctures during labor
EpiduralsLee Y et al. Reg Anaes Pain Med . May 2008.
Gaining Experience
• Appropriate specification equipment
• Use in non-neuraxial anaesthesia
• Outpatient evaluations
• Pre-puncture imaging
Spine Phantom
Spine Phantom
Ultrasound assessment of Gastric Content and Volume.
Perlas A et al. Anaesthesiology 2009. Jul 111 (1) 82-9.
“ Gentlemen…this is no humbug!”
Ultrasound for the Obstetric Anaesthetist – Tips and Tricks.J Loughrey OAA 3 day course. 2011.
Ultrasonography of the adult thoracic and lumbar spine for central neuraxial blockade.Chin KJ, Karmaker MJ, Peng P.Anesthesiol. 2011; 114: 1459-‐85.
Damage to the conus medullaris following spinal anaesthesia.Reynolds F.Anaesthesia 2001; 56: 238-‐247.
Ultrasonographic control of the puncture level for lumbar neuraxial block in obstetric anaesthesia.Schlotterbeck H, Shaeffer R, Dow WA et al.Br J Anaesth 2001; 100 : 230-‐4.
Ultrasound imaging facilitates spinal anaesthesia in adults with difZicult surface anatomical landmarks.Chin KJ et al.Anesthesiol. 2011: 115(1) 94-‐101.
Ultrasound using the transverse approach to the lumbar spine provides reliable landmarks for labor epidurals.Arzola C, Davies S, Rofaeel A, Carvahlo J.Anesth Analg 2007; 104 (5) : 1188-‐92.
Real-‐time ultrasound-‐guided paramedian epidural access: evaluation of a novel in-‐plane technique. Karmakar MK, Li X, Ho AM, Kwok WH, Chui PT. Br J Anaesth. 2009 Jun;102(6):845-‐54.
Ultrasound assessment of gastric content and volumePerlas A, Chan VW et al.Anesthesiol 2009; 111 (1): 82-‐9.
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